Note: Descriptions are shown in the official language in which they were submitted.
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TAP WITH INCORPORATED AIR PASSAGEWAY
It is known to provide moulded plastic taps for use with containers, in
particular disposable containers of the type popular for supplying liquid such
as water, wine or milk. One well known type of tap for this purpose is a so-
called push button tap having a resilient plastic diaphragm which, when
pressed, opens the valve to allow liquid to flow from the container. The
resilient plastic diaphragm, commonly referred to as a "push button", can be
arranged so that it positively urges the valve into a sealing position when
manual pressure is removed therefrom. The tap is therefore self-closing.
An alternative to push button taps are the so-called "rotary" taps. In
these, a cap is rotated to in turn rotate a stem within the tap body. Rotation
of
the stem causes it to uncover an aperture provided in the tap body through
which or from which liquid is dispensed. The problem with rotary taps is that
effective sealing of these is generally more difficult to achieve than with
push
button taps. Furthermore rotary taps are not self closing.
Irrespective of the type of tap used with a container, it has been found
that smooth liquid flow with a stabilised flow profile can only be achieved if
either the container is flexible and collapses as liquid is dispensed or the
container is vented. The reason for this is that otherwise air must flow into
the
container to fill the space from which liquid has been vacated and equalise
the
pressure within the container. The inflow of air disrupts the outflow of
liquid
causing it to be uneven and reducing the flow rate.
The present invention is directed towards the provision of a self closing
tap which will give smooth liquid flow even with rigid closed containers. It
is
afurther object to provide a tap which will maximise the flow rate and in
addition give constant flow even when the container is near empty.
A tap in accordance with a first aspect of the invention comprises a
hollow body defining a liquid inlet, an air inlet, a liquid outlet and an air
outlet,
and a divider element dividing the interior of the body into a liquid flow
passageway between the liquid inlet and the liquid outlet and an air flow
passageway between the air inlet and the air outlet, a section of the air flow
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passageway being separated from the liquid flow passageway, the separate
section having an inlet and an outlet, a valve system for controlling liquid
and
air flow in the passageways, and a push button connected to the body for
operating the valve system, wherein the air inlet and the liquid outlet are
adjacent to each other and the valve system comprises a valve element, the
valve element being movable by pressure on the push button from a first
position in which it closes the liquid inlet and prevents liquid flow from the
tap
to a second position in which liquid flows from the tap, wherein the valve
element also controls air flow in the air flow passageway and the valve
element, when in the first position, is adjacent to but spaced from the outlet
of
the separate section of the air passageway.
A tap in accordance with a second aspect of the invention comprises a
hollow body defining a liquid inlet, an air inlet, a liquid outlet and an air
outlet,
and a divider element dividing the interior of the body into a liquid flow
passageway between the liquid inlet and the liquid outlet and an air flow
passageway between the air inlet and the air outlet, a section of the air flow
passageway being separated from the liquid flow passageway, the separate
section having an inlet and an outlet, a valve system for controlling liquid
and
air flow in the passageways, and a push button connected to the body for
operating the valve system, wherein the air inlet and the liquid outlet are
adjacent to each other and the valve system comprises a valve element
movable by pressure applied to the push button from a first position in which
it
closes the liquid outlet and prevents liquid flow from the tap to a second
position in which liquid flows from the tap, the valve element also
controlling
air flow in the air flow passageway and the valve element, when in the first
position, is adjacent to but spaced from the inlet to the separate section of
the
air passageway.
The advantage of both aspects is that by providing an airflow
passageway which is at least in part separately formed from the liquid flow
passageway, air can flow into to container simultaneously with dispensing of
liquid therefrom. Thus the pressure can continuously be equalised between
the interior of the container and the exterior, ambient, environment and the
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liquid will flow smoothly and at the maximum possible flow rate, dictated by
the size of the outlet, without requiring venting of a container with which
the
tap is used or collapse thereof.
The air inlet and liquid outlet are adjacent each other. The air outlet
may be adjacent the liquid inlet or it may be spaced therefrom, in particular
the air outlet may be provided such that, in use with the tap fixed to a
container, it is located within the container.
The valve system is preferably of the type comprising a valve seat, a
valve element and a valve stem connecting the valve element to the push
button.
In a preferred embodiment of the first aspect the air and liquid flow
passageways are both downstream of the valve seat, whilst in a preferred
embodiment of the second aspect they are both upstream of the valve seat.
In the first preferred embodiment, the valve seat is provided at the liquid
inlet
of the tap, whilst in the second, the valve seat is provided at the liquid
outlet.
The second permits of an airflow passageway which extends beyond the
liquid inlet and, in use, into the container with which the tap is employed.
The
first embodiment does not allow such an elongate airflow passageway and it
was unexpected that the air flow is still sufficient to establish smooth
liquid
flow.
The valve stem preferably moves in guide means. The guide means
assist in tap closure through guidance of the valve stem. The guide means, in
a form which is particularly suitable for the first preferred embodiment
discussed above, comprises first and second spaced guide sleeves. The
advantage of this, as will be discussed further below, is that a greater
portion
of the valve stem is wiped during passage through the guide means and liquid
thereon additionally has to traverse the air gap created by the spacing
between the sleeves which reduces the chances of it entering the push
button.
Very preferably in the first preferred embodiment the tap also
comprises a flexible member fixed between the valve stem and the tap body
which prevents liquid access to the push button. The flexible member serves
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the purpose of preventing pockets of liquid being caught in the push button
which can go sour and adversely affect the quality of subsequently dispensed
liquid.
The tap is preferably provided with a spout which in use can be
arranged vertically or generally vertically. In the first aspect the valve
stem
will move generally horizontally, i.e. transversely, or generally
transversely, to
the spout whilst in the second aspect the valve stem will move vertically,
i.e.
parallel to the axis of the spout. With the first aspect, the spout may
include a
dividing wall defining the liquid outlet and the air inlet as well as, in
part, the
air flow passageway and the liquid flow passageway, but in the second this is
not possible since it would prevent movement of the valve element within the
spout to open and close the tap.
The tap of the first aspect may be called a front push tap in that,
generally, manual pressure will be provided to the "front" of the container to
move the valve stem horizontally, has the advantage that only a very small
amount of the tap is between the container contents and the external
environment. Thus the air penetration through the tap is minimised, as too is
the decay of liquid carried within a container fitted with the tap. Another
advantage of this front push tap is that the pressure of the liquid remaining
in
the container tends to close the valve element against the valve seat when
manual pressure is removed from the push button.
A significant advantage of the tap of the second aspect, which may be
termed a top push tap as, generally, manual pressure will be applied from
above to move the valve stem vertically, is that no liquid will be trapped
between the valve element and the liquid outlet as the valve element is at the
liquid outlet which means that there is no chance of dripping nor of any
retained liquid going sour and then spoiling subsequently dispensed liquid.
The invention will now be further described by way of example with
reference to the accompanying drawings in which:-
Figure 1 is a side view partially sectional of first embodiment of a tap in
accordance with the invention in the closed, non-liquid dispensing, position;
Figure 2 is a view similar to Figure 1 but enlarged and showing the tap
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in the open liquid dispensing position;
Figure 3 is an end view taken in the direction of arrow III of Figure 1 but
with the valve element omitted;
Figure 4 is a similar view to Figure 1 but showing an alternative guide
means for the tap;
Figure 5 is a transverse section through a second embodiment of a tap
in accordance with the invention in the closed, non-liquid dispensing
position;
Figure 6 is a vertical section through the tap of Figure 5 but in the
open, liquid dispensing, position, and,
Figure 7 is a similar view to Figure 6 and Figures 7A and 7B are
sections taken along lines A-A and B-B, but shaded to show liquid and air
flow.
The tap 2 shown in Figures 1 to 3 comprises a body 4 having an inlet
portion 6 and a body portion 8 which meet at a liquid inlet 10 which in this
embodiment is also the air outlet. The body portion 8 includes a liquid outlet
12 and an air inlet 13 at the end of a spout 14. The body portion 8 extends
from the inlet 10 across the outlet 12 and is closed at the other end by push
button 16. The body 4 may be formed from any suitable material such as
high-density polyethylene, low-density polyethylene, polypropylene or linear
low-density polyethylene. The button 16 needs to be resilient but flexible so
that it is capable of large deformation under manual pressure but
subsequently resuming its original shape when the pressure is removed. The
button 16 is suitably formed from an elastomeric polymer, for example
ethylene vinyl acetate, metallocene polythene or polybutylene terephthlate.
The inlet portion 6 is formed with screw threads 18 to allow attachment
of the tap 2 to a liquid container. It will be appreciated that the tap 2 can
be
attached to a container in other ways but a connection which is not destroyed
on removal of the tap 2 after emptying of the container may be preferred
because it makes the tap 2 reusable.
The tap 2 is provided with a valve system for controlling liquid and air
flow therethrough. In the tap 2 of Figures 1 to 3 the valve system serves to
provide a seal at the inlet 10 and comprises a valve element 20 carried on a
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valve stem 22. The valve element 20 is frustoconical and has a flared mouth
and a sealing bead 21 (see Figure 4). The inlet 10 is formed with walls 24
which have a corresponding frustoconical shape.
The valve stem 22 extends through guide means comprising a guide
collar 26 and is connected to a elongate boss 28 which protrudes downwardly
from the button 16, the end of the valve stem 22 being press or snap fit in a
correspondingly shaped aperture 30 in the boss 28. The locking of the button
16 to the valve stem causes press fitting of the button skirt within a rim 31
formed at the end of the body portion 8 across the outlet 12 from the inlet 10
which forms a seal between the button 16 and body portion 8.
The spout 14 is divided into the two outlets 12, 13 and into two
passages 34, 36 by an intermediate wall 38. The wall 38 stems from a flange
40 which extends diagonally across the body portion to divide the interior
into
two regions. The flange 40 includes a central aperture banded by guide collar
26 through which the valve stem 22 moves and an upper aperture 41. The
aperture 41 provides the connection between the two regions into which the
flange 40 divides the interior of the tap body portion 8. The flange 40 may
have a part-circular boss 42 which with the adjacent wall of the body portion
8
defines a passage 43 extending from aperture 41.
In the position shown in Figure 1, in which the button 16 is unpressed,
the frustoconical valve element 20 seats in the frustoconical walls 24 of the
inlet 10 and sealing bead 21 is compressed against the walls 24 so that no
liquid can flow from a container with which the tap 2 is used. When pressure
is applied to the button 16, the valve stem 22 and frustoconical valve element
24 move into the inlet portion 6 of the tap 2 towards the container which
unseats the valve element 20 from the valve seat constituted by the
frustoconical walls 24. As a result liquid can flow from the container around
the valve element 20 and into the body portion 8 as shown by the arrows in
Figure 2. The liquid will flow against the flange 40 and pass down the
passage 34 of the spout 14.
The outflow of liquid will cause a reduction in pressure in the container
which will draw air up through the passage 36 into the second region of the
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interior of the body portion. The air will flow through aperture 41, passage
43
and around the valve element 20 and into the container. It was unexpected
that this return air could "jump" across the valve into the main body of the
container in sufficient small volume packets to establish smooth flow by
filling
the space created on outflow of the liquid from the tap 2. The result is
stabilisation of the liquid flow profile and in addition maximum flow rate.
This
liquid oufflow does not have to cease to allow air inflow due to the provision
of
the two passages 34, 36.
It has been found that the volume of the air passageway formed by
passages 36 and 43 and the second region of the body portion 8 can be much
less than that of the liquid passageway formed by passage 34 and the first
region of the body portion 8 and in particular that satisfactory results can
be
achieved with a liquid to air passageway volume ratio of 6:1.
In Figures 1 to 3, the liquid outlet 12 and air inlet 13 are shown
adjacent each other but it should be noted that the air inlet 13 could be
provided elsewhere, for example, in the top wall of the body portion 8, "top"
being understood in the sense of the Figures. In this case wall 38 would not
be required and flange 40 would be arranged to separate the second region
from the spout 14 with the spout 14 then providing solely the liquid outlet
12.
One problem with known taps, as mentioned above, is the potential for
contamination of liquid carried in a container to which the tap is fitted.
Contamination can occur through oxygen transmission through the tap itself
which can occur via two mechanisms: firstly permeation through the polymer
molecular structure of the components of the tap, and secondly through micro
channels at the interfaces of the tap components.
The tap 2 of Figures 1 to 3 minimises oxygen ingress through both of
these mechanisms. As to the first, the surface area of plastic which is acting
as a barrier between the liquid and the container and ambient surrounding air
is minimal being simply the valve element 20 and a very small region of the
body adjacent the screw threads 18. In many known taps other tap
components are available for oxygen transmission, in particular the button
which because of its necessary flexible nature can be a large source of
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oxygen transfer. As to the second, the only interface between the liquid and
the ambient surrounding air is between the valve element 20 and the inlet
walls 24.
It is expected that typically the tap 2 of Figures 1 to 3 will give an
improvement in oxygen transmission rate of 3, that is the oxygen transmission
will be reduced by at least two thirds. The result will be significantly
extended
pre-dispensing shelf life which is important, particularly for containers used
for
wine.
Figure 4 shows an alternative version of the tap 2 of Figures 1 to 3.
The majority of the parts are the same and therefore like reference numerals
will be used for like parts.
The major change is that the guide means comprises a second guide
sleeve 44 spaced from the first 26. In addition, the first guide sleeve 26 is
comparatively longer than that of the tap 2 of Figures 1 to 3. Liquid on the
surface of the stem 22 following dispensing has therefore to pass through two
relatively long sleeves 26 and 44 which will tend to "wipe" off the liquid and
allow it to drop down through liquid passage 34. In addition, the spacing
between the guide sleeves 26 and 44 provides an air gap which will tend to
cause liquid to fall and pass out through air passage 36. Thus the system
prevents liquid on the surface of the stem 22 from being drawn back into the
button 16. This is advantageous because liquid in the button could drain
down the air passage 36 when the button is pressed which could upset the air
return mechanism and also contaminate liquid then being dispensed from the
container into a receptacle.
As shown in Figure 4, the second guide sleeve 44 may in fact be
configured as a bellows or gaiter which is tagged to both the valve stem 22
and the body portion 8 so as to move with the valve stem 22 on pressing and
release of the button 16. The skirt 46 extending between the second guide
sleeve 44 and the body portion 8 will provide a complete barrier to liquid
entering the button 16.
The tap 2 of Figures 1 to 3 and 4 may be termed a "front push" tap, in
that, as connected to a container, pressure is applied to the button 16 in a
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direction generally towards the front of the container.
The tap of Figures 5 to 7 on the other hand could be termed a "top
push" tap in that, as will be seen and described in detail below, pressure is
applied downwards.
The tap 52 has many parts in common with tap 2 including an inlet
portion 56 and a body portion 58 separated by a liquid inlet 60, the body
portion 58 being formed with a spout 64 providing a liquid outlet 62 which in
this embodiment is also the air inlet. A button 66 carries a valve stem 72
which in turn carries a valve element 70 having a sealing bead 71. The valve
element 70 is frustoconical with a flared mouth such that when tap 52 is
closed, sealing bead 71 on the element 70 seats at the annular edge of the
spout 64 to seal the outlet 62.
One advantage of the top push tap 52 is that the tap 52 is valved at the
liquid outlet, that is, there is no gap between the valve element 70 and the
liquid outlet 62 where liquid can be retained when dispensing ceases which
would subsequently form drips.
The valve stem 72 is again connected to the button 66 by connection to
a boss 78 which protrudes downwardly from the button 66. In this
embodiment the valve stem 72 carries fins 82 at its opposite end above the
valve element 70.
As the valve element 70 moves within the spout 64, the spout 64
cannot be divided as in the tap 2. However, above the valve element 70, the
interior of the body portion 58 is again separated into two regions by a
flange
element 84. Flange element 84 has a first inner circular portion surrounding a
central aperture 86 in which the valve stem 72 moves and a second outer
region extending around approximately 270 and having two-downwardly
depending fins 88 at its ends. The flange element 84 may be moulded as part
of the body portion 58 and in addition to dividing that body portion 58 into
two
regions acts as a solid valve guide. The fins 88 thereof are therefore held
static within the body portion 58 and the valve fins 82 are arranged to run
adjacent and parallel to the static fins 88.
The static fins 88 define with the walls of the body portion 58 a first air
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flow passage. The tap 52 includes a second air flow passage in the form of a
pipe 90 which extends from flange element 84 transversely to the fins 88 and
beyond the inlet portion 56.
As with the tap 2, on depression of the button 66 the tap 52, the valve
element 70 unseats and liquid flows along a liquid flow passageway defined
by the first region into which the body portion 58 is divided by flange 84 and
out of the spout 64, to one side of the valve element 70. Simultaneously air
flows in through the passage defined by static fins 88, into the second region
of the body portion 58, through pipe 90 and into the container via outlet 90.
The air and liquid flows are illustrated clearly in Figures 7, 7A and 7B.
The results in terms of maximisation of liquid flow rate and smooth flow
profile may in some instances be even better with top push tap 52 than with
front push tap 2 because the location of the valve element 70 at the outlet
permits the relatively elongate protruding pipe 90 which facilitates air
return.
